Using v3 CS-Cart. Trying to get Authorize.net working. Signed up for an account, got approved, did all the things needed on Authroize.net end, followed the guide on here to intigrate with cs-cart, and everytime I try to place a test order, I get this:
(TESTMODE) Credit card transactions are not accepted by this merchant.
I have also tried setting it to live mode, as well as on authorize.net end, and same deal.
Verify that you have your correct API LoginID (Login) and APITxKey (Transaction key) are set correctly. That's the only way Anet knows who the merchant is. I believe it's telling you basically that one or the other (or both) those values are invalid.